Fuel Cell Components

ABSTRACT

A strip of fuel cell components ( 200 ) comprising: a plurality of fuel cell components ( 202 ) spaced apart in a first direction; an indexing structure ( 210 ) connected to the plurality of fuel cell components, the indexing structure configured to define the position of one of the plurality of fuel cell components in the first direction; wherein the indexing structure is made from a different material to the plurality of fuel cell components. A component transfer mechanism for transferring a fuel cell sub-component to a substrate, using a roller and transfer tape. A strip of fuel cell components with a sub-component which is rotatable about a pivot. An apparatus and a method for assembling a fuel cell by applying a sub-component to an underside of a strip moving on a conveyor.

The invention relates to the field of fuel cells, and to fuel cellcomponents and a method of assembly of a fuel cell stack in particular.

Electrode or separator plates for fuel cells, that is, in the form ofanode or cathode plates, need to meet stringent requirements to avoid orremove any contamination, and typically require a series of differentprocessing steps to be applied before the plates can be assembled into afuel cell stack. Various types of coatings and other surface treatmentsmay be required. Given that volume production of fuel cell partsrequires a large number of such plates to be handled in rapidsuccession, a solution that enables accurate, economical andreproducible preparation and assembly of fuel cells is required.

In accordance with a first aspect of the invention there is provided astrip of fuel cell components comprising:

-   -   a plurality of fuel cell components spaced apart in a first        direction;    -   an indexing structure connected to the plurality of fuel cell        components, the indexing structure configured to define the        position of one of the plurality of fuel cell components in the        first direction;    -   wherein the indexing structure comprises a different material to        the plurality of fuel cell components.

The indexing structure can enable the positioning of fuel cellcomponents at build points within a fuel cell stack to be performed moreeasily, more reproducibly or more reliably. The provision of theindexing structure also allows the transfer of fuel cell subcomponentsheld on a carrier to a fuel cell plate to be performed more easily, morereproducibly or more reliably. The provision of an indexing structure ofa different material allows for a fuel cell stack to be produced morecheaply as the indexing material need not be made from the same,typically expensive, material as fuel cell plates. Thus, the fuel cellcomponents do not need to include means to index the strip as theindexing function is provided by the indexing structure of differentmaterial. Optionally, the indexing structure of different materialsolely provides the indexing function for the strip over at least partof the strip in the first direction.

The indexing structure may be releasably or severably connected to theplurality of fuel cell components. The releasably or severablyconnection of the indexing structure can assist in providing an indexingstructure of a different material to the fuel cell plates.

The plurality of fuel cell components may comprise a plurality of fuelcell assemblies. A fuel cell assembly may comprise a fuel cell plate.The plurality of fuel cell components may comprise a first end plate, aplurality of fuel cell assemblies and a second end plate, in that orderextending in the first direction. Providing end plates on the indexingmaterial can further ease the assembly process of the fuel cell stack.

The indexing structure may comprise a plurality of indentations or holesfor engaging with an indexor in order to define the position of one ofthe plurality of fuel cell components.

The indexing structure may be connected to the plurality of fuel cellcomponents by at least one spot weld.

The indexing structure may comprise a lateral fold region betweenadjacent fuel cell components.

The indexing structure may comprise a plurality of electricallyconductive tracks that are insulated from one another.

According to a further aspect of the invention there is a fuel cellstack comprising a folded strip of fuel cell components as definedabove.

According to a further aspect of the invention there is provided amethod of assembling a fuel cell stack, the method comprising:

-   -   indexing the strip of fuel cell components according to any        preceding claim in order to locate a fuel cell component at a        build position.

The method may further comprise removing the indexing structure from thefuel cell component at the build position.

The indexing structure may comprise a lateral fold region betweenadjacent fuel cell components. The method may further comprise foldingthe indexing structure at the lateral fold regions in order to locate aplurality of fuel cell components at the build position.

According to a further aspect of the invention there is provided acomponent transfer mechanism for transferring a fuel cell sub-componentto a substrate, the component transfer mechanism comprising:

-   -   a rotatable roller; and    -   a transfer tape that passes around the roller and is held in        tension such that rotation of the roller results in movement of        the transfer tape, wherein the transfer tape defines an outer        surface configured to carry the fuel cell sub-component;    -   wherein the component transfer mechanism is movable relative to        the substrate in a first direction, which is transverse to a        plane of the substrate, between a component transfer position in        which the transfer tape on the roller is adjacent the substrate        and a raised position in which the transfer tape on the roller        is spaced apart from the substrate; and    -   wherein the rotatable roller is configured to be rotated such        that the sub-component on the transfer tape is located in        between the roller and the substrate when the component transfer        mechanism is in the component transfer position.

The rotatable roller may be configured to be rotated at the same timethat the component transfer mechanism is moved from the raised positionto the component transfer position.

The component transfer mechanism may be movable relative to thesubstrate in a second direction that is parallel to a longitudinal axisof the substrate, which can progressively lay down the sub-component onthe substrate.

The speed of the transfer tape around the roller may be faster than thespeed of the substrate relative to the component transfer mechanism inthe second direction in order to provide relative motion between thesub-component and the strip in the second direction.

The roller may have a radius that is sufficiently small in order tocause a transverse edge of the fuel cell sub-component to be detachedfrom the transfer tape as it passes around the roller.

The substrate may comprise a strip of fuel cell components. The fuelcell sub-component may comprises a laminate layer comprising one or moreof a gas diffusion layer, a first layer of catalyst, an electrodemembrane and a second layer of catalyst. The substrate may comprise agasket with an aperture, into which the laminate layer is to be placed.

According to a further aspect of the invention there is provided amethod of transferring a fuel cell sub-component to a substrate using acomponent transfer mechanism, the component transfer mechanismcomprising:

-   -   a rotatable roller; and    -   a transfer tape that passes around the roller and is held in        tension such that rotation of the roller results in movement of        the transfer tape, wherein the transfer tape defines an outer        surface configured to carry the fuel cell sub-component;

the method comprising:

-   -   moving the component transfer mechanism relative to the        substrate in a first direction, which is transverse to a plane        of the substrate, between a component transfer position in which        the transfer tape on the roller is adjacent the substrate and a        raised position in which the transfer tape on the roller is        spaced apart from the substrate; and    -   rotating the rotatable roller such that the sub-component on the        transfer tape is located in between the roller and the substrate        when the component transfer mechanism is in the component        transfer position.

According to a further aspect of the invention there is provided a stripof fuel cell components comprising a first sub-component that isrotatably connected to a second sub-component about a pivot, wherein thefirst sub-component is movable about the pivot between:

-   -   a first position that is parallel with a plane of the strip;    -   a second position that is out of the plane of the strip; and    -   a third position that is parallel with the plane of the strip        and is different to the first position.

The first sub-component may be adjacent to the second sub-component inthe plane of the strip in the first position. The first sub-componentmay overly the second sub-component in the third position.

The strip of fuel cell components may further comprise a flexiblejoining region between a first transverse edge of the firstsub-component and the second sub-component. The flexible joining regionmay be configured to provide the pivot.

The strip of fuel cell components may further comprise a severablejoining region associated with a second transverse edge of the firstsub-component. The severable joining region may be configured toreleasably attach the first sub-component to a different secondsub-component.

According to a further aspect of the invention there is provided amethod of assembling a fuel cell from a strip of fuel cell components,the strip of fuel cell components comprising a first sub-component thatis rotatably connected to a second sub-component about a pivot, themethod comprising:

-   -   applying a first force to the first sub-component in a first        direction that is transverse to the plane of the strip in order        to move it from a first position that is parallel with a plane        of the strip to a second position that is out of the plane of        the strip; and    -   applying a second force to the first sub-component in a second        direction that is parallel to the plane of the strip in order to        move the first sub-component from the second position to a third        position that is parallel with the plane of the strip and is        different to the first position.

According to a further aspect of the invention there is provided anapparatus for assembling a fuel cell from a strip of fuel cellcomponents, the apparatus comprising:

-   -   a first force applicator configured to apply a first force to        the first sub-component in a first direction that is transverse        to the plane of the strip in order to move it from a first        position that is parallel with a plane of the strip to a second        position that is out of the plane of the strip; and    -   a second force applicator configured to apply a second force to        the first sub-component in a second direction that is parallel        to the plane of the strip in order to move the first        sub-component from the second position to a third position that        is parallel with the plane of the strip and is different to the        first position.

The apparatus may further comprise a separator configured to separate asecond transverse edge of the first sub-component from a neighbouringsecond sub-component.

The first force applicator may be a pusher. The second force applicatormay be a roller.

According to a further aspect of the invention there is provided anapparatus for assembling a fuel cell comprising:

-   -   a conveyor for moving a strip of fuel cell components in a first        direction that is parallel to a longitudinal axis of the strip        of fuel cell components in order to locate a sub-component        receiving portion of the strip of fuel cell components at a        build point;    -   a component application mechanism for applying a sub-component        to an underside of the sub-component receiving portion of the        strip of fuel cell components at the build-point.

The component application mechanism may comprise a pusher configured tomove the sub-component from a first position that is spaced apart fromthe strip of fuel cell components to a second position in which thesub-component is in contact with an adhesive surface on the underside ofthe strip of fuel cell components.

The apparatus may comprise a magazine for receiving a plurality ofsub-components. The component application mechanism may be configured toapply a force to a bottom sub-component in the magazine in order totranslate a top sub-component in the magazine to the second position.

The component application mechanism may be configured to apply a forceto a sub-component that is located in a pocketed tape in order totranslate the sub-component to the second position. The componentapplication mechanism may comprise a pusher and a mechanism forlaterally indexing the pocketed tape.

The apparatus may further comprise a support block that is movablebetween a first position that is spaced apart from an upper surface ofthe strip of fuel cell components, and a second position that isadjacent to the upper surface of the strip of fuel cell components, suchthat in the second position the support block is configured to preventthe strip of fuel cell components from moving as the sub-component isapplied to the underside of the strip of fuel cell components.

According to a further aspect of the invention there is provided amethod of assembling a fuel cell comprising:

-   -   moving a strip of fuel cell components in a first direction that        is parallel to a longitudinal axis of the strip of fuel cell        components; and    -   applying a sub-component to an underside of the strip of fuel        cell components.

Another strip of fuel cell components is also disclosed. The stripcomprises:

-   -   a plurality of fuel cell components spaced apart in a first        direction, the plurality of fuel cell components comprising a        first surface;    -   a support structure connected to the plurality of fuel cell        components, the support structure comprising two lateral fold        regions between adjacent fuel cell components such that the        support structure is foldable in order for the first surfaces of        the plurality of fuel cell components to face in the same        direction when folded.

Each of the plurality of fuel cell components may be considered tocomprise a common first surface. The first surfaces of the plurality offuel cell components may be on a first surface of the strip.

The two lateral fold regions of the support structure between adjacentfuel cell components may ensure that the first surfaces of the pluralityof adjacent fuel cell components to face in the same direction whenfolded.

The provision of the support structure that enables all of the cells toface in the same direction when folded provides a simplification for themethod of manufacture of the fuel cell. Separate positioning ofindividual fuel cell components within the stack can be avoided.

The fuel cell components may comprise one or more of a gas diffusionlayer or a membrane electrode assembly.

The support structure may be releasably or severably connected to theplurality of fuel cell components. The provision of a releasable orseverable support material allows for a more efficient method ofmanufacture, as the support can be produced using a cheaper, sacrificialmaterial and need not be made from the same material as the fuel cell.

The fuel cell components may be substantially planar.

The plurality of fuel cell components may comprise a plurality of fuelcell assemblies and a plurality of spacing components. A spacingcomponent may be provided between adjacent fuel cell components.Alternatively, the plurality of fuel cell components may comprise aplurality of fuel cell assemblies and a plurality of voids. A void maybe provided between adjacent fuel cell components. The spacingcomponents, voids and fuel cell assemblies may be of a similar length inthe first direction.

The plurality of fuel cell components may comprise a plurality of fuelcell assemblies. The support structure may comprise two lateral foldregions between adjacent fuel cell assemblies.

The plurality of fuel cell components may each comprise a secondsurface, which opposes the first surface. The support structure may befoldable such that the first surface of a fuel cell component faces thesecond surface of an adjacent fuel cell component when the strip isfolded.

The support structure may be connected to both sides of the plurality offuel cell components. Alternatively, the support structure may beconnected to only one side of the plurality of fuel cell components.

The support structure may comprise an electrical connection to a fuelcell component to which it is connected. The support structure maycomprise an indexing structure.

The plurality of fuel cell components may comprise a first end plate, aplurality of fuel cell assemblies and a second end plate, in that order,extending in the first direction.

The first surface of the first end plate may be an external face of afuel cell stack. The first surface of the second end plate may be aninternal face of a fuel cell stack. The second surface of the first endplate may be an internal face of a fuel cell stack. The second surfaceof the second end plate may be an external face of a fuel cell stack.

The support structure may comprise only one fold region between thefirst end plate and the plurality of fuel cell assemblies. The supportstructure may comprise only one fold region between the second end plateand the plurality of fuel cell assemblies.

There may be provided a device configured to form the strip of fuel cellcomponents.

There is also disclosed a method of assembling a fuel cell stack, themethod comprising:

-   -   folding a strip of fuel cell components according to any        preceding claim in order to locate a plurality of fuel cell        components at a build position in order to form a fuel cell        stack.

The method may further comprise removing at least a portion of a supportstructure from the plurality of fuel cell components at the buildposition. Removing at least a portion of the support structure from theplurality of fuel cell components at the build position may compriseleaving a portion of the support structure comprising an electricalconnection connected to the plurality of fuel cell components.

There is also disclosed a method of assembling a fuel cell stack, themethod comprising:

-   -   locating a first strip of partial fuel cell components over a        second strip of partial fuel cell components; and    -   fan folding the first and second strips of partial fuel cell        components together in order to assemble a fuel cell stack.

Such a method provides a simple and convenient way to assemble a fuelcell stack as separate positioning of individual fuel cell componentswithin the stack can be avoided.

Fan folding the first and second strips of partial fuel cell componentstogether may comprise locating a partial fuel cell component that is ina first region of the first strip adjacent to a partial fuel cellcomponent that is in a corresponding region of the second strip in orderto define a complete fuel cell. In this way, individual fuel cells canbe reliably and consistently constructed within the fuel cell stack.

One or both of the strips of partial fuel cell components may comprise asupport structure. Such support structures may have two lateral foldregions between adjacent partial fuel cell components. A spacing elementmay be located between the two lateral fold regions that are betweenadjacent partial fuel cell components. The step of fan folding the firstand second strips of partial fuel cell components together may comprisecausing the partial fuel cell components of the first strip and secondstrip to contact each other through the spacing element. Providing suchspacing elements can provide for a simplified method of assembly as apartial fuel cell component in the first strip can be adjacent to apartial fuel cell component in the second strip on both sides whenfolded, and vice versa.

There is also disclosed a fuel cell stack comprising:

-   -   a first strip of partial fuel cell components; and    -   a second strip of partial fuel cell components;    -   wherein the first and second strips of partial fuel cell        components are located one over the other in a fan folded        orientation in order to define the fuel cell stack.

A partial fuel cell component that is in a first region of the firststrip may be located adjacent to a partial fuel cell component that isin a corresponding region of the second strip in order to define acomplete fuel cell.

The first strip of partial fuel cell components may comprise a supportstructure connected to the partial fuel cell components. Additionally oralternatively, the second strip of partial fuel cell components maycomprise a support structure connected to the partial fuel cellcomponents.

One or both of the support structures may comprise two lateral foldregions between adjacent partial fuel cell components. A spacing elementmay be located between the two lateral fold regions that are betweenadjacent partial fuel cell components. A spacing element may have anopening that is configured to allow components to contact each otherthrough the thickness of the strip. In this way, a simplifiedarrangement of components on the strip can be used as the spacingelements can ensure that partial fuel cell components in the first stripare adjacent to a partial fuel cell component in the second strip onboth sides when folded, and vice versa.

For example, one side of the partial fuel components in the first stripcan be directly adjacent to the second strip, and the other side of thepartial fuel components in the first strip can be exposed to the secondstrip through the opening in the spacing element.

The first and/or second strip of partial fuel cell components maycomprise one or a plurality of electrically conductive tracks forproviding an electrical connection to one or more of the fuel cells inthe fuel cell stack from externally of the stack. The electricallyconductive track may be associated with any support structure disclosedherein. The electrically conductive track or tracks may extend in adirection along the length of the strip. The plurality of electricallyconductive tracks may each have a node for external connection at oneend and may be connected to a fuel cell at the other end. Differentelectrically conductive tracks may be connected to different fuel cellsin the fuel cell stack, and may be individually addressable by theassociated nodes. The plurality of nodes may be located at the same endof the strip, optionally on an external connector frame.

The partial fuel cell components of the first strip and the second stripmay together comprise one or more of: a first electrode; a membrane, asecond electrode, a cathode gas diffusion layer (which collectively maybe referred to as a four layer membrane electrode assembly), an indexingstructure (which may comprise a first indexing structure and a secondindexing structure), a shim, a gasket, an anode gas diffusion layer anda bipolar plate.

The partial fuel cell components of the first strip may comprise one ormore of: a first electrode; a membrane, a second electrode, a cathodegas diffusion layer (which collectively may be referred to as a fourlayer membrane electrode assembly), a first indexing structure and asecond indexing structure. The partial fuel cell components of thesecond strip may comprise one or more of: a shim, a gasket, an anode gasdiffusion layer and a bipolar plate.

The second strip may comprise a current collector plate at one end andan external connector frame at the other end. A node that iselectrically connected to the current collector plate may be provided onthe external connector frame. The node may be for external connection tothe fuel cell stack.

Embodiments of the present invention may be better understood withreference to the accompanying drawings, in which:

FIGS. 1 a and 1 b show a process for manufacturing a fuel cell;

FIG. 2 shows a schematic of a strip comprising a plurality of fuelcells;

FIG. 3 shows three side views of a schematic of a folded strip;

FIGS. 4 a and 4 b show a schematic of a strip and a carrier;

FIGS. 5 a and 5 b show a schematic of a strip and a case;

FIG. 6 a shows a schematic of a portion of a fuel cell production line;

FIG. 6 b shows an alternative schematic of the portion of the fuel cellproduction line of FIG. 6 a;

FIG. 6 c shows a schematic of a portion of another fuel cell productionline;

FIG. 7 shows a method of assembling a fuel cell stack;

FIG. 8 shows another method of assembling a fuel cell stack;

FIG. 9 shows a further method of assembling a fuel cell stack;

FIGS. 10 a to 10 e illustrate a strip of fuel cell components andapparatus for assembling a fuel cell from the strip;

FIGS. 11 a to 11 e illustrate schematically the operation of a componenttransfer mechanism for transferring a fuel cell sub-component to asubstrate;

FIG. 12 shows a further method of transferring a fuel cell sub-componentto a substrate using a component transfer mechanism;

FIG. 13 shows a method of assembling a fuel cell from a strip of fuelcell components; and

FIG. 14 shows a method of assembling a fuel cell.

FIGS. 1 a and 1 b show schematically a process 100 for manufacturing afuel cell. FIG. 1 is used to describe how the provision of a supportstructure allows a fuel cell stack to be constructed from a strip offuel cells that are aligned in the same direction when the strip isfolded such that the fuel cells form a stack.

FIG. 1 is broken down into a number of occupied frames 102, 108, 112,116, 120, 124. The occupied frames 102, 108, 112, 116, 120, 124 showsuccessive operations for the formation of a fuel cell. The occupiedframes 102, 108, 112, 116, 120, 124 are each separated from one anotherby empty frames 103, 109, 113, 117, 121. The empty frames will bediscussed in further detail with relation to FIG. 2.

In each occupied frame 102, 108, 112, 116, 120, 124, the fuel cell isillustrated such that the cell has a left side edge 105 and a right sideedge 107 in the plane of the cell. For clarity, equivalent features inthe various occupied frames 102, 108, 112, 116, 120, 124 of FIG. 1 areonly labelled in the frame in which they are first discussed.

In a first frame 102, a bipolar plate 104 is shown. The bipolar plate104 may be a pressed plate. The bipolar plate 104 is substantiallyplanar. The bipolar plate 104 has a weld point 106 adjacent to each ofits corners. Two weld points 106 are positioned on the left side edge105 of the bipolar plate 104 and two weld points 106 are positioned onthe right side edge 107 of the bipolar plate 104. The weld points 106are configured to be welded to a separate support structure such as anindexing track using a spot welding technique. Alternatively, thesupport structure may be configured to clip on to the ‘weld points’. Assuch, the term ‘weld point’ should be construed broadly to encompass anysite configured to be severably or removably coupled with an additionalstructure. A “weld point” may also be referred to as a “connectionpoint”.

In a second frame 108, the bipolar plate 104 has been welded to a leftside indexing structure 110 a that runs along the length of the leftside edge 105 of the bipolar plate 104 and to a right side indexingstructure 110 b that runs along the length of the right side edge 107 ofthe bipolar plate 104 in a first direction. The first direction isgenerally parallel with the side edges 105, 107 of the bipolar plate 104and an axial direction of the indexing structures 110 a, 110 b.

The left and right side indexing structures 110 a, 110 b are examples ofsupport structures that may be used to couple multiple fuel cellstogether. In addition to the support capability, the indexing structurescan provide the additional benefit of enabling alignment of the fuelcells and their components. The left side indexing structure 110 a isseverably, or releasably, connected to the bipolar plate 104 at the weldpoints 106 on the left side edge 105 of the bipolar plate 104. The rightside indexing structure 110 b is severably, or releasably, connected tothe bipolar plate 104 at the weld points 106 on the right side edge 107of the bipolar plate 104.

The indexing structures 110 a, 110 b are configured to define theposition of one of the plurality of fuel cell components in the firstdirection. The indexing structure allows manufacturing equipment totrack the position of fuel cell components more easily more reproduciblyand/or more reliably, so that correct spacing between components can bemaintained. In this way, the provision of the indexing structure allowsfor improved automated handling fuel cell plates by alleviating some ofthe difficulties associated with the positioning of individual plateswithin a fuel cell stack.

The indexing structures 110 a, 110 b comprise a plurality ofindentations or holes for engaging with an indexor (not shown in thedrawings) in order to define the position of one of the plurality offuel cell components. The manufacturing equipment may comprise anelectronic camera and image recognition software so as to identify theposition of the indexing structures 110 a, 110 b and the relativeposition of fuel cell components, such as bipolar plates 104. Such anarrangement can provide for a cheaper, quicker and/or more accurateprocess for manufacturing a fuel cell or fuel cell stack.

In the example shown in FIG. 1, the indexing structures 110 a, 110 b maybe used to provide automated recognition of the position of fuel cellcomponents with reference to the support structure. The indexingmaterial can therefore be used to simplify the construction of fuelcells, or to improve the performance of automated techniques thatconstruct fuel cells. The use of an indexing structure in the improvedformation of a fuel cell stack will be described further below withreference to FIG. 2.

The indexing structures 110 a, 110 b can be formed of a different typeof material to the bipolar plate 104. That is, the indexing structures110 a, 110 b is formed/made exclusively of (consists only of) adifferent type of material to the bipolar plate 104. For example, theindexing structures 110 a, 110 b may be formed of mild steel orpolyethylene naphthalate (PEN). Providing the indexing structures 110 a,110 b as a different type of material from the bipolar plate 104 canreduce the cost of materials used in the manufacture of the bipolarplate 104. Indeed, the additional cost of the extra indexing structures110 a, 110 b may not be significant through suitable choice ofmaterials. The indexing structures 110 a, 110 b may be made from a lesscostly material than the bipolar plate 104 as it can have less stringentrequirements, such as electrical conductance characteristics.

Alternatively, it may be convenient in some applications for the leftand right side indexing structures 110 a, 110 b to be the same as eachother, or at least to be made of the same material as each other, inorder to further reduce the complexity of manufacture.

In a third frame 112, an over-mold process is used to apply a liquidinjection molding (LIM) seal 114 around the extremity of the bipolarplate 104. The over-mold process allows a polymer to be applied to ametal substrate that extends beyond the die of the mold whilst avoidingunwanted extrusion of the polymer seal material.

In a fourth frame 116, a die cut process is used to form a subgasket 118and a lamination technique is used to apply the subgasket 118 to thebipolar plate 104.

In a fifth frame 120, an anode gas diffusion layer 122 is placed withinthe subgasket 118 on the surface of the bipolar plate 104 and bonded inplace using a lamination technique. Welding, bonding or the use of aretaining means such as an adhesive are examples of bonding methods thatmay be suitable.

In a final, sixth frame 124, a four layer fuel cell membrane lamination126 is applied and bonded over the anode gas diffusion layer andsubgasket. The four layer cell membrane 126 comprises the followinglayers: a first electrode; a membrane, a second electrode; and a cathodegas diffusion layer. The arrangement of subcomponents illustrated in thesixth frame 124 is referred to as a fuel cell. Such a fuel cell can bepositioned on top of other fuel cells to provide a fuel cell stack.

It will be appreciated from the description that follows that the fuelcell shown in the sixth frame 124 of FIG. 1 can be provided by more thanone strip of partial fuel cell components.

FIG. 2 illustrates a strip 200 comprising three fuel cells 202 a, 202 b,202 c similar to the one illustrated in the last frame of FIG. 1 b.Three views of the strip 200 are illustrated: a top down view 201(similar to the view in FIG. 1); an extended side-on view 203; and afolded side-on view 205.

From the top down view 201, it can be seen that the fuel cells 202 a,202 b, 202 c are all severably welded to a left side support structure210 a and a right side indexing structure 210 b. The left and right sideindexing structures 210 a, 210 b are similar to those applied by theprocess illustrated in FIG. 1. The indexing structures 210 a, 210 b arean example of support structures. It will be appreciated that a supportstructure may be provided that does not comprise indexing material.

The strip 200 comprises a succession of occupied and empty frames. Theoccupied frames each comprise a fuel cell 202 a, 202 b, 202 c. The fuelcells 202 a, 202 b, 202 c consist of fuel cell components. The fuelcells 202 a, 202 b, 202 c are spaced apart in a first direction. Theindexing structures 210 a, 210 b extend in the first direction andconnect the plurality of fuel cell 202 a, 202 b, 202 c. The plurality offuel cell 202 a, 202 b, 202 c comprise a first surface that faces in thesame direction when the strip of fuel cells 202 a, 202 b, 202 c is laidflat.

The empty frames 204 a, 204 b do not comprise a fuel cell 202 a, 202 b,202 c, but may be considered to comprise indexing structures 210 a, 210b, as the indexing structures extend in the first direction adjacent toboth the fuel cells 202 a, 202 b, 202 c and to voids that make up theempty frames 204 a, 204 b. The length of the indexing structures 210 a,210 b in the occupied frames is similar to that of the indexingstructures 210 a, 210 b in the empty frames 204 a, 204 b.

In the extended side-on view 203, an anode side of each of the fuelcells 202 a, 202 b, 202 c and a cathode side of each of the fuel cells202 a, 202 b, 202 c can be seen on the respective first surfaces 206 andsecond surfaces 208 of the fuel cells 202 a, 202 b, 202 c. Thisarrangement of the fuel cells is different from the example shown inFIG. 1, in which both the anode and cathode gas diffusion layers areprovided on a single side of the bipolar plate. It will be appreciatedthat the processes and strips of components described herein can beimplemented irrespective of how each individual fuel cell isconstructed.

Fold lines 212 are superimposed on the strip 200 as seen in the top downview 201 and the extended side-on view 203. The fold lines 212 arepositioned at the intersection of the occupied and empty frames; thefold lines 212 represent lateral fold regions between the adjacent fuelcells 202 a, 202 b, 202 c and empty frames 204 a, 204 b. The indexingstructures 210 a, 210 b comprise two lateral fold regions betweenadjacent fuel cells 202 a, 202 b, 202 c. The support structure 210 a,210 b comprising two lateral fold regions 212 between adjacent fuel cellcomponents 202 a, 202 b, 202 c means that the support structure isfoldable such that the first surfaces of the plurality of fuel cellcomponents face in the same direction when the strip 200 is folded.

In the folded side view 205, the strip 200 is fan folded so as to form astack of cells. From the folded side view 205 it can be seen that by theprovision of empty frames 204 a, 204 b between the fuel cells 202 a, 202b, 202 c, the first surfaces 206 of the plurality of fuel cells 202 a,202 b, 202 c face in the same direction when the indexing structure isfolded. Similarly, second surfaces 208 of the fuel cells 202 a, 202 b,202 c also face in the same direction when the indexing structure isfolded. As the orientation of the anode and cathode sides of the cellsis therefore the same for all of the plates, a simplified method ofconstruction can be employed to form the stack as all of the plates canbe easily aligned.

In some examples, the fuel cells 202 are connected to only one supportor indexing structure 210 a, 210 b. That is, only one side of the cells202 may be connected to a support or indexing structure. In someexamples, a strip is provided in which each frame between two indexingstructures 210 a, 210 b has a fuel cell 202. That is, initially thereare no empty frames. The strip of fuel cells can then be separated intotwo strips, with each strip comprising one of the support structures 210a, 210 b and alternate fuel cells 202. In this way, each of the twostrips has alternate empty frames in the spaces that have been vacatedby the fuel cells 202 that are part of the other strip.

FIG. 3 illustrates three side views of a folded strip 300. A fan foldedside view 301 shows the same arrangement illustrated in the folded sideview 205 of FIG. 2. A second view 303 shows the folded strip undercompression, forming a fuel cell stack. A third view 305 shows the fuelcell stack secured with tie bars 306.

In the second view 303, a first end plate assembly 302 and a second endplate assembly 304 are provided. The first end plate assembly 302 is incontact with the first surface of the top fuel cell. The second endplate assembly 304 is in contact with the second surface of the bottomfuel cell. In addition to the features illustrated in the second view303, insulator frames of material may be provided at the respective endsof the strip 300 to separate and provide electrical insulation betweenthe fuel cells and the end plates 302, 304. The insulator frames may beprovided by the support structure. That is, the support structure may beretained in the final fuel cell stack and extend, at the respective endsof the strip 300 of fuel cells, to form an insulating layer between thestrip 300 and the end plates 302, 304. Alternatively, the insulatorframes may be provided by nylon sheets that are connected to the supportstructures at weld points on the sheets.

In the second view 303, external compression is applied in a directionnormal to the plane of the fuel cells of the stack in order for theseals and gaskets between the fuel cells to function correctly.

In the third view 305, tie bars 306 have been used to secure the stackin compression. The external compressive force is therefore no longerrequired. At this stage in the production of the fuel cell stack, theindexing structures can be removed. Alternatively, the indexingstructures could be removed before or during compression. This removalcan be achieved by, for example, melting or cutting the welds that linkthe fuel cells to the indexing structures. A laser trimming process maybe employed to sever the welds that link the bipolar plates and theindexing strips. However, in some embodiments, some or all of theindexing material may be retained in the end product and not be severedfrom the fuel cells. The retained indexing material may be used toprovide additional features to the cell, as will be apparent from theexamples provided in FIGS. 4 and 5.

In some embodiments of the invention, a carrier may be employed to carryat least some subcomponents of a fuel cell. The use of carriers cansimplify the manufacture of a fuel cell comprising multiple structures.Combinations of a carrier and indexing structures can further improvethe reproducibility of component placement by automated systems andenable an increase in production speed.

FIGS. 4 a and 4 b illustrate a strip 400 a, 400 b of fuel cellsubcomponents and a carrier 401 a, 401 b. The carrier 401 a, 401 b islaid over the strip 400 a, 400 b before the strip 401 a, 401 b is fanfolded to form the fuel cell stack. In this way, the fuel cell stackalternately comprises, in a direction through the thickness of the fuelcell subcomponents, a region of the strip 400 a, 400 b and a region ofthe carrier 401 a, 401 b.

The strip 400 a, 400 b of fuel cell subcomponents is an example of afirst strip of partial fuel cell components. The carrier 401 a, 401 b isan example of a second strip of partial fuel cell components. It will beappreciated from the description that follows that the strip 400 a, 400b and carrier 401 a, 401 b can be located one over the other, and thenfan folded together in order to assemble a fuel cell stack.

Two views of the strip 400 a, 400 b and carrier 401 a, 401 b are shown.In the view shown in FIG. 4 a, four layer membrane electrode assemblies402 a (similar to those of FIG. 1) are shown separate from the carrier401 a. Also, anode gas diffusion layers 404 a are shown separate fromthe strip 400 a in FIG. 4 a. In FIG. 4 b, the four layer membraneelectrode assemblies 402 b are laminated on to the carrier 401 b, andthe anode gas diffusion layers (GDL) 404 b are laminated on to the strip400 b. Other than these details, the structure of the carrier 401 a, 401b and the strip 400 a, 400 b are similar in FIGS. 4 a and 4 b. Thefeatures of the carrier 401 b and the strip 400 b are discussed infurther detail below with reference to FIG. 4 b.

The strip 400 b comprises a plurality of partial fuel cells 406, eachpartial fuel cell comprising a plurality of subcomponents including inthis example a shim and gasket, an anode gas diffusion layer and abipolar plate. The construction of the partial fuel cells 406 is similarto the fuel cells shown in the fifth frame of FIG. 1.

Spacing elements 408 are provided between the adjacent partial fuelcells 406. The spacing elements 408 are located between two lateral foldregions that are between adjacent partial fuel cells 406. That is,partial fuel cells 406 and spacing elements 408 alternate along thelength of the strip. Each spacing element 408 has an opening that allowscomponents to contact each other through the thickness of the strip. Inthis way, a simplified arrangement of components on the strip can beused as the spacing elements 408 can ensure that each partial fuel cellcomponent in the strip 400 b is adjacent to the fuel cell components inthe carrier 401 b, and vice versa.

In some embodiments, the spacing elements 408 define gaps or voidsbetween partial fuel cells 406. That is, the spacing elements 408 maynot comprise any components of a fuel cell. In other embodiments,including those for air-breathing fuel cell stacks, the spacing elements408 may comprise a cathode shim together with a second cathode gasket(optionally provided with adhesive) that forms a seal when the strip 400b is folded-up to define the fuel cell stack. That is, the spacingelements 408 may comprise components of a fuel cell, and therefore maybe considered as a partial fuel cell component.

The spacing elements 408 have similar dimensions to the partial fuelcells 406 and may be formed from the same sheet of material as theplate/shim and gasket 400 a, 400 b, indexing structure or any fuel cellsubcomponent. At least part of the spacing elements 408 and the partialfuel cells 406 may be made from a continuous laminated material that isprofiled in form to define parts of both the spacing elements 408 andthe partial fuel cells 406.

Each of the partial fuel cells 406 is connected to an adjacent spacingelement 408 along a fold line at the intersection of the fuel cells 406and spacing elements 408. Therefore, two fold lines are provided betweenadjacent fuel cell components. In some examples, the spacing elementscan themselves comprise fuel cell components. In such examples, thespacing elements and the partial fuel cells do not comprise commoncomponents. As such, common components are not provided in adjacentframes of the strip.

The fold line may be considered to pass through a fold region 407. Inthis example, the fold region 407 is provided by cutting away themajority of material between the fuel cells 406 and spacing elements408. The position of the fold region 407 may be located using indexingmaterial (not shown) that can be provided on the strip 400 a, 400 b orcarrier 401 a, 401 b and extend normal to the first direction along alength of the strip 400, 400 b. Two coupling portions 409 are providedbetween adjacent fuel cells 406 and spacing elements 408. The couplingportions 409 can be considered to perform the function of shims.

Alternatively, the fold region may comprise a region of weakenedmaterial joining the fuel cells 406 and spacing elements 408. Such ajoin, which may be referred to as a ‘living hinge’ can be designed towithstand repeated folding and unfolding steps, sufficient to subject astack of plates to fan folding. The line of weakened material may beprovided by a series of perforations.

The carrier 401 b comprises a four layer membrane electrode assembly 402b, a first indexing structure 410 down a first side of the four layermembrane electrode assembly 402 b, and a second indexing structure 412down a second side for the four layer membrane electrode assembly 402 b.It will be appreciated that either or both of the strip 400 a, 400 b andcarrier 401 a, 401 b can be considered as providing the indexingstructure.

A partial fuel cell component that is in a first region of the strip 400b is located adjacent to a partial fuel cell component that is in acorresponding region of the carrier 401 b in order to define a completefuel cell. That is, complete fuel cells are provided when the strip 400b is located next to the carrier 401 b and fan folded to define a stack.The first region of the strip 400 b may be considered as components thatare between adjacent fold lines (for example a fuel cell 406 in FIG. 4b), or it may be considered as components that are either side of a foldline (for example a fuel cell 406 and a spacing element 408 in FIG. 4b).

The membrane electrode assemblies (MEAs) 402 b are fixed in place on thecarrier material and separated from other MEAs 402 b by voids 414. Thevoids 414 are examples of spacing elements. It will be appreciated thatthe voids 414 in the carrier 401 b do not necessarily have to align withthe spacing elements 408 in the strip 400 b.

The indexing structures 410, 412 each comprise a plurality ofelectrically conductive tracks 416 that are insulated from one another.The electrically conductive tracks 416 are each in electrical contactwith either anode or cathode side of a cell to facilitate either (i)monitoring of cell performance or (ii) provision of current collection.Each of the electrically conductive tracks 416 extend along a respectivelength of one of the indexing structures 410, 412. The electricallyconductive tracks 416 can be used to draw off current from the fuelcells when they are assembled into a stack. It will be appreciated thatin an alternative embodiment, one or more or all of the fuel cells couldshare a conductive track.

FIGS. 5 a and 5 b show a fuel cell case 502 a, 502 b and a strip 504 offuel cells 506 with similarities to the structure formed by thecombination of the strip and carrier in FIG. 4. In addition to thefeatures of the strip and carrier of FIG. 4, the strip 504 of FIG. 5comprises a current collector plate 514, an external connector frame 520and an insulator frame 522. In this example, the base 502 a of the casecomprises a first end plate and the top 502 b of the case comprises asecond end plate.

A first insulating frame 508 of the strip 504 of fuel cells 506 has beenplaced in a base of the case 502 a. A fuel cell stack may be formed byfolding the strip 504 of fuel cells 506, 507 along lateral fold lines510 that separate the fuel cells 504 and empty frames 512. The emptyframes 512 are examples of spacing elements. A lateral fold line 510 isprovided at the extremities of each of the empty frames 512. Once thefuel cells 506, 507 are all within the base 502 a, a lid of the case 502b may be placed on top of the folded fuel cells in order to complete thefuel cell stack.

The strip 504 of FIG. 5 differs from the strip shown in FIG. 4 in anumber of ways. For example, a current collector plate 514 is providedon the first insulating frame of the strip 504 and an external connectorframe is provided at the other end of the strip 504. The conductiveplate 514 is insulated from the first end plate provided in the base 502a of the case by the first insulating frame 508. The current collectorplate 514 is coupled to a conductive track 516 that runs along a supportstructure 518 to the external connector frame 520 at the other end ofthe strip 502. The fuel cells 506 are also coupled to similar conductivetracks 516 for current monitoring. The conductive tracks 516 terminateat nodes 518 on the external connector frame 520. The current collectorplate 514, conductive tracks 516 and nodes 518 may comprise a materialsuch as copper. As can be seen from FIG. 5 b, the nodes 518 are exposedfor external connection when the stack is constructed.

The fuel cell 507 nearest to a portion of the strip 502 that will formthe top of the stack may be referred to as the top fuel cell 507. Thetop fuel cell 507 is adjacent to an optional spacing element (emptyframe) 512. The spacing element 512 is adjacent to an insulator frame522 that comprises an electrically insulating material. The insulatorframe 522 separates the lid 502 b, which forms a second end plate, fromthe top fuel cell 507 when the stack is folded. The insulator frame 522is separated from the external connector frame 520 by an end spacingelement 513. However, the function of the end spacing element 513differs from that of the rest of the spacing elements 512; the lateralfolds at the extremities of the end spacing element 513 are each folded90 degrees with respect to the adjacent frames 520, 522. The end spacingelement 513 allows the connector frame 520 to be positioned on theexterior of the second end plate that is built into the top of the case502 b. The surface of the insulator frame 522 shown in FIG. 5 a does notface in the same direction as the surface of the connector frame 520when the strip is folded.

FIG. 5 b illustrates a fan folded view of the strip 504 seen in FIG. 5a. The distance in the direction through the stack is exaggerated forclarity. The angle between adjacent fuel cells 506 and the carrierportions of empty frames 512 approaches 180 degrees (where the fuel cellthickness is small compared to its width) when the strip 504 is folded.

Pressure pads 524 may be provided on a surface of connector frame 520that opposes the surface on which the conductive nodes 518 are provided.The pressure pads 524 can provide a pressure absorbing layer between thesecond end plate provided in the top 502 b of the case and the connectorframe 520. The provision of the pressure pads 524 may prevent damage tothe stack when a compressive force 526 is applied to the fuel cell stackand can offer compliance and maximise or increase contact betweenelectrically conductive surfaces. The compressive force 526 is requiredto engage and seal via compression the cells and gaskets of the variouscell cells 506, 507 within the stack and to enable final stack assembly,as is known in the art.

FIG. 6 a shows an apparatus for assembling a fuel cell, which may be aportion of a production line 600 for a fuel cell stack 602. Theproduction line 600 comprises a conveyor 604, which may be a conveyorbelt, for moving a strip of fuel cell components in a first directionthat is parallel to a longitudinal axis of the strip of fuel cellcomponents in order to locate a sub-component receiving portion of thestrip at a build point. Only the support structure 606 of the strip offuel cell components is shown in the side view of FIG. 6 a. The firstdirection is shown schematically in FIG. 6 a with arrow 603, and is inthe plane of the strip of fuel cell components as they pass through theapparatus. The first direction in this example is horizontal.

The conveyor 604 may have an indexor (not shown) that is configured tointeract with indexing on the support structure 606 associated with aplurality of fuel cell as fuel cell subcomponents. The indexor can movethe strip of fuel cell components in the first direction in order tolocate the sub-component receiving portion of the strip at a buildpoint. For example the conveyor 604 may only engage with side edges ofthe support structure 606. The support structure 606 comprises a numberof frames.

The apparatus in this example further comprises a first componentapplication mechanism (which may be referred to as a bottom applicationmechanism 608) and optionally a second component application mechanism(which may be referred to as a top application mechanism 610). Thebottom application mechanism 608 is configured to applysub-components/structures such as manifold seals to an underside of thesub-component receiving portion of the strip at the build-point. The topapplication mechanism 610 can place fuel cell subcomponents on the topof the strip of fuel cell components so as to form a complete fuel cell612 in a frame of the support structure 606. It will be appreciated thatin some examples only one application mechanism may be required.

In this example the bottom application mechanism 608 comprises a pusher609 configured to move a sub-component 611 from a first position that isspaced apart from the strip of fuel cell components in a seconddirection to a second position in which the sub-component 611 is incontact with an adhesive surface (not shown) on the underside of thestrip of fuel cell components. The second direction 605 is shown in FIG.6 a with arrow 605 and is transverse to the first direction 603.

In this example the bottom application mechanism 608 also comprises amagazine 611, in which is stacked a plurality of sub-components 611 forlocating on the strip of fuel cell components as it passes over the topof the magazine 611. For each desired location on the strip, the pusher609 is extended upwards in order to apply a force to a bottomsub-component in the magazine, thereby translating a top sub-componentin the magazine to the second position against the strip such that theadhesive on the strip can join the sub-component 611 to the strip. Thepusher 609 can then be retracted such that the second sub-component 611from the top of the stack in the magazine can be moved away from thesub-component that has been joined to the strip. In this way, the stripcan be conveniently indexed on without engaging with the nextsub-component 611 in the magazine.

The sub-component 611 that is applied by the bottom applicationmechanism may be one or more manifold seals, a corrugated cathode plate,or any other component, in some examples a relatively rigid componentsuch as a metallic component.

Using such a bottom application mechanism can avoid a need for pick andplace handling of the strip of fuel cell components, which can beparticularly advantageous in examples where the strip has delicatecomponents that could be damaged by such pick and place operation. Alsobeneficially, control of the position of the strip of fuel cellcomponents and the sub-components 611 can be maintained such that a moreaccurately assembled fuel cell stack can be achieved.

FIG. 6 b illustrates a view from below of the bottom applicationmechanism of FIG. 6 a engaging with a strip of fuel cell components. Thetop view in FIG. 6 b shows a sub-component 631 in a first position thatis spaced apart from a sub-component receiving portion 632 of the stripof fuel cell components. The bottom view in FIG. 6 b shows that thesub-component 631 has been moved to the second position by a pusher 639.In the second position, the sub-component 631 is in contact with anadhesive surface (not shown) on the underside of the sub-componentreceiving portion 632 of the strip of fuel cell components.

Also shown in FIG. 6 b is a support block 633 that is also movablebetween a first position (as shown in the top view) and a secondposition (as shown in the bottom view). The support block 633 is used toprevent the strip of fuel cell components from moving as thesub-component is applied to the strip of fuel cell components frombelow. In the first position the support block 633 is spaced apart froman upper surface of the strip of fuel cell components. In the secondposition, the support block 633 is adjacent to the upper surface of thestrip. Use of such a support block can enable better adhesion to beprovided between the underside of the strip and the sub-component 631 asa greater compression force can be applied to the two components.

FIG. 6 c illustrates an alternative assembly apparatus that comprises abottom application mechanism, which in this example is a pusher 658. Inthis example, instead of the sub-components being provided in amagazine, as in FIGS. 6 a and 6 b, the sub-components 651 are providedto a second position for joining to the strip of fuel cell components652 by a preformed pocketed tape 660. The tape is labelled withreference 660′ in FIG. 6 c when it is loaded with a sub-component 651and is labelled with reference 660″ after the sub-component 651 has beenremoved. Such pocketed tape 660 is known in the art and can beadvantageous as it can be used to accurately align the sub-componentsfor subsequent adhesive pick-off.

In FIG. 6 c, a component application mechanism is provided for moving asub-component 651 from a first position that is that is spaced apartfrom the strip of fuel cell components (the four sub-components 651 thatare furthest left in FIG. 6 c are in the first position) to a secondposition in which the sub-component 651 is in contact with the undersideof the strip of fuel cell components 652 (the sub-component 651 that isabove the pusher 658 in FIG. 6 c). The component application mechanismin this example includes both the pusher 658, as described above, and amechanism for laterally indexing the pocketed tape 660 from left toright. Alternatively, the mechanism can be considered as just the pusher658 such that the sub-component 651 is in the first position when it isbetween the pusher 658 and the strip 652, but before the pusher 658 hasmoved the sub-component 651 into contact with the strip 652. Either way,the component application mechanism is configured to apply a force to asub-component that is located in a pocketed tape in order to translatethe sub-component to the second position.

Also shown in FIG. 6 c is an optional cover tape 661 that can maintainthe sub-components in a desired location in the pocketed tape 660 as itis transferred to the pusher 658. The cover tape 663 can be rolled ontoa take-up spool 663 before the associated sub-component 651 is put intothe second position for joining to the strip 652.

The combination of the production line 600 and the features of the stripof fuel cell component described previously reduces the physical spacerequired to build a fuel cell stack, enables a significant amount ofautomation to be provided, and can improve the reproducibility andaccuracy of the construction of a fuel cell stack.

The conveyor 604 can deposit fuel cells 612 formed by the applicationmechanisms 608, 610 into a case 614. The fuel cells 612 may be alignedby a process of self-alignment in the case 614 such that a first surfaceof each of the fuel cells is properly aligned. The first surface of eachof the fuel cells in the stack can face in the same direction as thesame first surfaces of the fuel cells when they are laid flat in thestrip.

It will be appreciated that any feature of an embodiment describedherein may be combined with a feature or features of any otherembodiment where it is practicable to do so. For example, the productionline of FIG. 6 could be used with a plurality of strips of partial fuelcell components such as the two that are shown in FIG. 5.

FIG. 7 illustrates a method of assembling a fuel cell stack. The methodcomprises a first step 701 of folding a strip of fuel cell components inorder to locate a plurality of fuel cell components at a build position.The method also comprises an optional second step 702 of removing atleast a portion of the support structure from the plurality of fuel cellcomponents at the build position. Removing at least a portion of thesupport structure from the plurality of fuel cell components at thebuild position may comprise a third step 703 of leaving a portion of thesupport structure connected to the plurality of fuel cell components.

The remaining portion of the support structure can provide for anelectrical connection to be made to the stack. In this way, the supportstructure can both hold fuel cell components during construction of thefuel cell stack and provide electrical connections to the stack.

FIG. 8 illustrates a method of assembling a fuel cell stack. The methodcomprises a first step 801 of indexing a strip of fuel cell componentsthat comprise an indexing structure in order to locate a fuel cellcomponent at a build position. The use of the indexing structure allowsfor a simplified method of assembling a fuel cell stack. The use of theindexing structure may also allow for the more accurate or reproducibleplacement of fuel cell stack components at the build position.

The method also comprises an optional second step 802 of removing theindexing structure from the fuel cell component at the build position.

The method may also comprise a third step 803 and a fourth step 804. Theindexing structure of the fuel cell stack can comprise a lateral foldregion between adjacent fuel cell components. At the third step 803, theindexing structure can be folded at the lateral fold regions in order tolocate a plurality of fuel cell components at the build position. At thefourth step 804, the indexing structure can be removed from theplurality of fuel cell components at the build position. The removal ofthe indexing structure may allow for the final dimensions of the fuelcell stack to be reduced.

FIG. 9 illustrates a method of assembling a fuel cell stack. The methodcomprises a first step 901 of locating a first strip of partial fuelcell components over a second strip of partial fuel cell components. Thefirst strip and second strip together may define a plurality of fuelcells.

The method continues with fan folding the first and second strips ofpartial fuel cell components together in order to assemble a fuel cellstack at step 902.

The method of FIG. 9 provides a convenient, accurate and reproduciblemeans of assembling a fuel cell stack.

FIGS. 10 a to 10 e illustrate a strip of fuel cell components 1000 andapparatus for assembling a fuel cell from the strip of fuel cellcomponents 1000. In particular, the strip 1000 includes a firstsub-component 1002 that is rotatably connected to a second sub-component1004 about a pivot 1006. The first sub-component 1002 is movable aboutthe pivot 1006 between a first position that is parallel with a plane ofthe strip (as shown in FIGS. 10 a and 10 b), a second position that isout of the plane of the strip (as shown in FIG. 10 c), and a thirdposition, which is different to the first position, that is parallelwith the plane of the strip (as shown in FIGS. 10 d and 10 e). In thisway, a fuel cell can conveniently be assembled by folding the firstsub-component 1002 back onto the second component 1004, as describedbelow.

FIG. 10 a shows the strip of fuel cell components 1000. The strip 100comprises first sub-components 1002 and second sub-components 1004alternately provided along the length of the strip 1000. The strip 1000in this example also includes a support structure 1008 that is coupleddirectly to each of the second sub-components 1004. Each firstsub-component 1002 is rotatably connected to an adjacent secondsubcomponent 1004 along a first transverse edge 1007. A transverse edgeis one that is transverse to a longitudinal direction of the strip 1000.The first sub-components 1002 may be rotatably connected to an adjacentsecond subcomponent 1004 by flexible joining sections 1011 that extendfrom the first transverse edge 1007. In this way the joining sections1011 define the pivot 1006. The joining sections 1011 may bemechanically weaker than the adjacent portions of the first and secondsub-components. In one example the joining sections may be regions ofreduced thickness compared with the first and second sub-components1002, 1004, for example they may be scored in order to encouragerotation of the first sub-component 1002 relative to the secondsub-component.

Optionally, one or more of the first sub-components 1002 may bereleasably connected to an adjacent second subcomponent 1004 along asecond transverse edge 1009. The second transverse edge 1009 is oppositeto the first transverse edge 1007. The first transverse edges 1007 arelabelled in FIG. 10 a as fold lines. The second transverse edges 1009are labelled in FIG. 10 a as shear lines, as will be understood from thedescription of FIG. 10 c below.

The first transverse edge 1007 is a trailing edge of the firstsub-component 1002 in the direction of travel of the strip 1000 relativeto an apparatus for assembling a fuel cell, as will be described below.Similarly, the second transverse edge 1009 is a leading edge of thefirst sub-component 1002.

The first sub-components 1002 are shown in FIG. 10 a in the first potionin which they are parallel with the plane of the strip 1000, and alsospaced apart from each adjacent second sub-component 1004 in a directionthat is in the plane of the strip 1000. When the first sub-components1002 are in the first position they may be conveniently located fortransferring the strip 1000. Also, it may be convenient to directlymanufacture the strip 1000 with the first sub-components 1002 in thefirst position using known techniques.

FIG. 10 b illustrates an apparatus for assembling a fuel cell from thestrip of fuel cell components 1000 shown in FIG. 10 a. The strip 1000moves through the apparatus in a direction that is in the plane of thestrip 1000 and is parallel to the longitudinal axis of the strip 1112,as shown with arrow 1013 in FIG. 10 b.

The apparatus includes a first force applicator, which in this exampleis a pusher 1012. The pusher 1012 is configured to apply a first forceto the first sub-component 1002 in a first direction 1016 that istransverse to the plane of the strip 1000 in order to move the firstsub-component 1002 about the pivot 1006 from its first position (asshown in FIG. 10 b) that is parallel with the plane of the strip 1012 toits second position that is out of the plane of the strip 1012 (as shownin FIG. 10 c). The pusher 1012 shown in FIG. 10 b applies a force to alower surface of the first sub-component 1002 in an upwards direction,which is an example of a direction that is transverse to the plane ofthe strip 1002. The lower surface may be referred to as an engagementsurface of the first sub-component. In this way, the first sub-component1002 is rotated about the second sub-component 1004 such that it extendsout of the plane of the strip 1000 as shown in FIG. 10 c. It will beappreciated that in other examples the first force applicator could be acomponent that pulls the first sub-component 1002 from its firstposition to its second position.

In this example, the apparatus also includes a separator 1016 that isconfigured to separate the second transverse edge 1009 of a firstsub-component 1002 from the neighbouring second subcomponent 1004 beforethe first sub-component 1002 is moved from its first position to itssecond position. As shown in FIGS. 10 b and 10 c, the separator 1016 ismovable in a direction that is transverse to the plane of the strip 1000in order to mechanically sever a severable joining region 1022 betweenthe two sub-components, although it will be appreciated that any otherseparator could be used. In some examples, an independent separator maynot be required as the action of the pusher 1012 can cause any severablejoining regions 1022 associated with the second transverse edge 1003 ofthe first sub-component 1002 to be broken.

FIG. 10 c shows the first sub-component 1002 in the second position,with its second transverse edge 1009 spaced apart from the plane of thestrip 1000. In this example, the pusher 1012 has moved through anaperture in the strip that has been produced by the displacement of thefirst sub-component 1002 from the first position to the second position.In this way, the lower/engagement surface or second transverse edge 1009of the first sub-component 1002 is exposed for a subsequent assemblyoperation that applies a second force to the first sub-component 1002 ina second direction 1018 that is parallel to the plane of the strip 1000in order to move the first sub-component 1002 from the second positionto a third position that is parallel with the plane of the strip 1000.The third position is different to the first position. This subsequentassembly operation is performed by a second force applicator, which inthis example is a pair of rollers 1014. It will be appreciated from thedescription that follows that the second position is any position thatallows the second force applicator to move the first sub-component fromthe second position to the third position.

FIG. 10 d illustrates the strip 1000 having moved towards and throughthe rollers 1014 from the position shown in FIG. 10 c. In this way thesecond force in the second direction 1018 has been applied by the toproller 1014 to the rightmost first sub-component 1002 in order to moveit to the third position. In the third position, the first sub-component1002 is parallel with the plane of the strip 1000 and overlies thesecond sub-component 1004 that was adjacent to its first transverse edge1007 in the first position. In this way, the first and secondsub-components 1002, 1004 are no longer spaced apart in the plane of thestrip 1000, as they were in the first position as shown in FIG. 10 a.

Use of one or more rollers 1014 can be advantageous as it causes thefirst sub-component 1002 to be progressively laid down on the secondsub-component 1004, which can provide a progressive wet-out orprogressive peel-off. That is, the rotation of the roller 1014 can beused to gradually increase the contact area between the firstsub-component 1002 and the second sub-component 1004, with the increasedcontact area growing in the second direction 1018 from a transverse edgeof the first sub-component 1002. This can reduce the likelihood that anyair bubbles are caught between the sub-components 1002, 1004 as theyshould be pushed out as the first sub-component 1002 is gradually laiddown. Similarly the likelihood of any wrinkles forming in the firstsub-component 1002 can be recued.

FIG. 10 e illustrates a strip 1000 in which all of the firstsub-components 1002 in the strip 1000 have been moved to their thirdpositions. In some examples, a complete fuel cell may be provided byeach combination of first and second sub-components as shown in FIG. 10e.

FIGS. 11 a to 11 e illustrate schematically the operation of a componenttransfer mechanism 1100 for transferring a fuel cell sub-component 1110to a substrate, which in this example is a strip of fuel cell components1112. The component transfer mechanism 1100 includes a rotatable roller1102 and a transfer tape 1104 that passes around the roller 1102 and isheld in tension such that rotation of the roller 11102 results inmovement of the transfer tape 1104. The transfer tape 1104 defines aninner surface 1106 for contacting the roller 1102 and an opposing outersurface 1108. The outer surface 1108 of the transfer tape 1104 isconfigured to carry a fuel cell sub-component 1110 for placing on thestrip of fuel cell components 1112. The sub-component 1110 may bereleasably attached to the transfer tape 1104 by adhesive.

In this example, the sub-component 1110 is a laminate layer comprising agas diffusion layer (GDL), a first layer of catalyst, an electrodemembrane and a second layer of catalyst. The two catalyst layers and theelectrode membrane can be referred to together as a membrane electrodeassembly (MEA) comprising the electrode. The laminate layer is to bepositioned within a gasket in the strip 1112 such that fluid within thelaminate layer is kept inside the laminate layer.

The component transfer mechanism 1100 is movable relative to the strip1112 in a first direction 1114 that is transverse to the plane of thestrip 1112 in order to move the component transfer mechanism 1100 eithertowards or away from the strip 1112. The component transfer mechanism1100 can be moved between a raised position in which the transfer tape1104 on the roller 1102 is spaced apart from the strip 112 as shown inFIG. 11 a, and a component transfer position as will be described belowwith reference to FIG. 11 d.

The roller 1102 can also be rotatably driven, in some examplessimultaneously, such that the transfer tape 1104 moves around the roller1102 and correspondingly the sub-component 1110 moves towards the roller1102 such that the sub-component 1110 on the transfer tape 1104 islocated in between the roller 1102 and the strip 1112 when the componenttransfer mechanism is in the component transfer position. The roller1102 can be driven either directly or indirectly. As shown in FIG. 11 b,the roller 1102 has been rotated such that the sub-component 1110 hasmoved downwards such that it is on a region of the transfer tape 1104that is adjacent to the roller 1102 yet is still transverse to the planeof the strip 1112. Also as shown in FIG. 11 b, the component transfermechanism 1100 has been moved in the first direction 1114 such that theroller 1102 is closer to the strip 1112.

FIG. 11 c shows the component transfer mechanism 1100 in a position thatis approaching the component transfer position, which is shown in FIG.11 d. In FIG. 11 c, it can be seen that the plane of the sub-component1100 is tending towards the plane of the strip 1112 as the sub-component1108 moves around the roller 1102 as it continues to rotate. In thisexample the roller 1102 has a radius that is sufficiently small in orderto cause a transverse edge of the sub-component 1100 to be detached fromthe transfer tape 1104 as it passes around the roller 1102. That is, aleading edge 1116 of the sub-component 1110 moves away from the transfertape 1104 as the sub-component 1110 moves around the radius of theroller 1102. This is because the tack strength of the adhesive betweenthe sub-component 1110 and transfer tape 1104 is not great enough to actagainst the rigidity of the sub-component 1110 and bend thesub-component 1110 for the specific radius of the roller 1102. Theadhesive that is used between the sub-component 1110 and the transfertape 1104 may have preferential release characteristics; for example theadhesive may have a higher tack strength in tension than in peel. Thiscan advantageously assist in detaching the sub-component 1110 from thetransfer tape 1104 at an appropriate time, and in an appropriatelocation, for attaching it to the strip 1112.

In this example, the strip 1112 has a region of exposed adhesive 1020that will be contacted by the sub-component 1110 when it is in thecomponent transfer position.

As the component transfer mechanism 1100 arrives at the componenttransfer position as shown in FIG. 11 d, due to the continued rotationand lowering of the roller 1102, the sub-component 1110 is placedadjacent to the strip 1112 and is orientated in the same plane as thestrip 1112. The tack strength of the adhesive between the strip 1112 andthe sub-component 1110 is stronger than the tack strength of theadhesive between the sub-component 1110 and the transfer tape 1104 whenthe component transfer mechanism 1100 is in the component transferposition. This may in part be due to a reduced contact area between thesub-component 1110 and the transfer tape because of the curvature of theroller 1102 and the stiffness of the sub-component 1110.

FIG. 11 e shows the component transfer mechanism having been moved awayfrom the strip 1112 such that the sub-component 1110 has been left inposition on the strip 1112.

The strip 1112 can continuously or non-continuously be moved in a seconddirection 1118 relative to the roller 1102 in order to assist with thedetachment of the sub-component 1110 from the transfer tape 1104 and/orto move the roller 1102 to a different place on the strip 1112 fordepositing a subsequent sub-component. The second direction 1118 isparallel to a longitudinal axis of the strip 1112. In this way, therotation of the roller 1102 and movement of the roller 1102 in the firstdirection can be repeated for subsequent placement operations ofsub-components.

Progressively laying down the sub-component 1110 in this way can beadvantageous as it can provide a progressive wet-out or progressivepeel-off, as described above.

In some examples the speed of the transfer tape 1104 around the roller1102 may be faster than the speed of the strip 1112 relative to thecomponent transfer mechanism in the second direction 1118. In this way,the resulting relative motion between the sub-component 1110 and thestrip 1112 in the second direction 1118 can assist with correctlylocating the sub-component 1110 in a desired position. In the examplethat the sub-component is a laminate layer that is to be fitted snuglyinto an aperture in a gasket, the motion of the laminate layer relativeto the gasket can cause a leading edge of the laminate layer (which mayhave been detached from the transfer tape 1104 due to the stiffness ofthe laminate layer and the radius of the roller 1102) to abut an insidewall of the aperture in the gasket such that the remaining portion ofthe laminate layer fits tightly into the aperture. This can beparticularly advantageous for fuel cells as any gaps between thelaminate layer and gasket can enable a fuel cell fluid (such ashydrogen) to bypass an active area of the fuel cell, thereby degradingperformance.

The assembly method described with reference to FIGS. 11 a to 11 e maybe referred to as pitch hopping. Such an assembly method can beadvantageous as control over the location of the components can beretained at all times during the assembly, and therefore complicated andcostly location identification techniques do not have to be used toproperly align the components. In turn, this can lead to a moreaccurately assembled fuel cell.

FIG. 12 illustrates a method of transferring a fuel cell sub-componentto a substrate using a component transfer mechanism such as the onedescribed and illustrated with reference to FIGS. 11 a to 11 e. Inparticular, the component transfer mechanism may comprise at least arotatable roller; and a transfer tape that passes around the roller andis held in tension such that rotation of the roller results in movementof the transfer tape. As above, the transfer tape defines an outersurface configured to carry the fuel cell sub-component.

At step 1202 the method comprises moving the component transfermechanism relative to the substrate in a first direction, which istransverse to a plane of the substrate, between a component transferposition in which the transfer tape on the roller is adjacent thesubstrate and a raised position in which the transfer tape on the rolleris spaced apart from the substrate.

The method also includes, at step 1204, rotating the rotatable rollersuch that the sub-component on the transfer tape is located in betweenthe roller and the substrate when the component transfer mechanism is inthe component transfer position. In some examples steps 1202 and 1204may be performed at the same time.

FIG. 13 illustrates a method of assembling a fuel cell from a strip offuel cell components such as the one described and illustrated withreference to FIGS. 10 a to 10 e. The strip of fuel cell components maycomprise at least a first sub-component that is rotatably connected to asecond sub-component about a pivot.

At step 1302, the method includes applying a first force to the firstsub-component in a first direction that is transverse to the plane ofthe strip in order to move it from a first position that is parallelwith a plane of the strip to a second position that is out of the planeof the strip. This movement may be about a pivot. Subsequently at step1304; the method comprises applying a second force to the firstsub-component in a second direction that is parallel to the plane of thestrip in order to move the first sub-component from the second positionto a third position that is parallel with the plane of the strip and isdifferent to the first position. This movement may also be about thepivot.

FIG. 14 illustrates a method of assembling a fuel cell comprising thatcan be performed by the apparatus illustrated in FIGS. 6 a to 6 c. Themethod includes, at step 1402, moving a strip of fuel cell components ina first direction that is parallel to a longitudinal axis of the stripof fuel cell components in order to locate a sub-component receivingportion of the strip at a build point. At step 1402, the method includesapplying a sub-component to an underside of the sub-component receivingportion of the strip at the build-point.

It will be appreciated that any discussion of specific directions offorces or movement that are discussed in this document includes forcesand directions that have a component in the direction indicated. Suchforces and directions may also have components in other directions.

1. A strip of fuel cell components comprising: a plurality of fuel cellcomponents spaced apart in a first direction; an indexing structureconnected to the plurality of fuel cell components, the indexingstructure configured to define the position of one of the plurality offuel cell components in the first direction; and, wherein the indexingstructure comprises a different material to the plurality of fuel cellcomponents.
 2. The strip of fuel cell components of claim 1, wherein theindexing structure is releasably or severably connected to the pluralityof fuel cell components.
 3. The strip of fuel cell components of claim 1wherein the plurality of fuel cell components comprises a plurality offuel cell assemblies, each fuel cell assembly comprising a fuel cellplate.
 4. The strip of fuel cell components of claim 3, wherein theplurality of fuel cell components comprises a first end plate, aplurality of fuel cell assemblies and a second end plate, in that orderextending in the first direction.
 5. The strip of fuel cell componentsof claim 1, wherein the indexing structure comprises a plurality ofindentations or holes for engaging with an indexor in order to definethe position of one of the plurality of fuel cell components.
 6. Thestrip of fuel cell components of claim 1, wherein the indexing structureis connected to the plurality of fuel cell components by at least onespot weld.
 7. The strip of fuel cell components of claim 1, wherein theindexing structure comprises a lateral fold region between adjacent fuelcell components
 8. The strip of fuel cell components of claim 1, whereinthe indexing structure comprises a plurality of electrically conductivetracks that are insulated from one another.
 9. A fuel cell stackcomprising a folded strip of fuel cell components according to anypreceding claim.
 10. A method of assembling a fuel cell stack, themethod comprising: indexing the strip of fuel cell components accordingto any preceding claim in order to locate a fuel cell component at abuild position.
 11. The method of claim 10, further comprising removingthe indexing structure from the fuel cell component at the buildposition.
 12. The method of claim 10, wherein the indexing structurecomprises a lateral fold region between adjacent fuel cell components,the method further comprising: folding the indexing structure at thelateral fold regions in order to locate a plurality of fuel cellcomponents at the build position. 13-43. (canceled)